1. Field of the Invention
The present invention relates to spanwise blowing along a deflectable airfoil surface of an aircraft, and in particular to spanwise blowing a jet of air across a deflectable airfoil surface through a nozzle which is attached to and moves with the airfoil.
2. Description of the Related Art
Numerous methods and systems for increasing aerodynamic lift by blowing air over airfoil surfaces have been suggested and tested in the past. Such systems for enhancing aerodynamic lift may be broadly categorized in terms of the direction of air flow over the airfoil surfaces. The first broad category would include blowing compressed air in the same direction as the free stream air flow over the airfoil surface. Such blowing is hereinafter termed chordwise blowing. The second broad category would include blowing compressed air in a direction substantially tangential to the lifting or airfoil surface and perpendicular to the freestream airflow. Such blowing is hereinafter termed spanwise blowing along the airfoil surface. The present invention falls into the latter category of spanwise blowing, and further discussion is limited to the same.
The broad category of spanwise blowing across airfoil surfaces is normally addressed in one of two subcategories. The first involves spanwise blowing along the leading edge of the airfoil surface. An example of a study typical of such leading edge spanwise blowimg is presented in an article entitled "An Experimental Investigation of Leading Edge Spanwise Blowing," International Council of Aeronautic Sciences, ICAS-82-6.6.2, Beijing Institute of Aeronautics and Astronautics, Su Wenhan et al. Such leading edge spanwise blowing is generally directed to creating a more stable leading edge vortex above the wing or airfoil surface.
The second subcategory of spanwise blowing involves spanwise blowing near the hinge line of a control surface or trailing edge flap for the purpose of providing boundary layer control to prevent flow separation behind the wing and control surface. A typical example of a study directed to such trailing edge spanwise blowing is provided in the article "Effects of Spanwise Blowing and Reverse Thrust on Fighter Low Speed Aerodynamics," Journal of Aircraft, Volume 20, No. 2, Feb. 1983, by J. W. Paulson, Jr., et al. FIG. 3 illustrates a typical example of a prior art trailing edge spanwise blowing configuration. In FIG. 3 an airfoil flap or rudder 40 is deflectably fixed to a wing 41. Nozzles 42 are typically mounted in the aft section of the fuselage of the aircraft and are stationary with respect to flap 40. Air is ejected from the nozzles spanwise along the surfaces of flap 40.
The present invention is directed to the broad category of trailing edge spanwise blowing across control surfaces or flaps of an aircraft and distinguishes itself from prior art systems by the location of the nozzle which directs the air flow spanwise along the airfoil or flap surface.
It is an object of the present invention to provide an enhanced lift augmentation system for an aircraft utilizing spanwise blowing across the trailing edge control surfaces of the aircraft wherein the exit nozzle which direct the spanwise jet of air along the control surface is attached to and is movable with the control surface as it is deflected.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointd out in the appended claims.